By Lily / Last Updated January 26, 2021

The problem: USB pen drive not detected

Have you got mad with your pen drive because it can’t be detected or recognized by your computer? If you fall into this issue, you’ll lose access to all files and folders saved on the USB pen drive. Definitely you want to work it out to make your pen drive readable again and regain your data. Before I show you how to fix pen drive not readable, I’d like to share the probable reasons for the problem.

Reasons and quick fixes for "USB pen drive not detected” issue

When you find your USB pen drive not detected on your computer, there are several probable reasons:

1. There’s a problem with the USB port: in this situation, you may plug your USB flash drive into different ports to see if a particular port is damaged. You can get it repaired at the computer manufacturer’s repair center.

2. There’s a problem with the USB driver: in this case, you can use Device Manager to check the status of your USB driver. See if there's a yellow exclamation mark next to your flash drive in Device Manager, which indicates there is a problem with the driver. Right click on the device and select Properties to gain specific error message.

3. There’s a problem with the USB device:

• USB device is damaged physically: in this circumstance, you can hardly fix the corrupted pen drive by yourself. A professional data recovery service might be a nice choice.
• USB device is attacked by virus: at this time, you should kill the virus with antivirus software.
• USB device is formatted improperly: for this reason, you can find detailed solution in the next part.

Now you have the basic opinion about the issue pen drive not readable, let’s get straight to how to repair pen drive not detected.

How to repair pen drive not detected if not formatted correctly?

At this part, I’ll focus on the last reason mentioned above—USB device is formatted improperly. By “formatted improperly”, I mean the USB pen drive suddenly loses its partitions or becomes a RAW drive due to a virus attack or abrupt removal, or simply is assigned a used drive letter. I’ll show you how to repair pen drive not detected in the three situations separately.

AOMEI Partition Assistant Professional as a comprehensive partition manager can assist you in all the situations. Learn detailed steps to fix USB flash drive not recognized in Windows 10 below. These methods apply to other Windows operating systems as well. (PS.: The Demo Version is available for your free download)

Try Demo Win 10/8.1/8/7/XP
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Situation 1. No partitions on the USB pen drive

This problem can be solved by creating partitions on the USB flash drive or just recovering the partitions:

✔Create partitions

1. Connect your USB pen drive to your computer. Install and run AOMEI Partition Assistant. Right click on the unallocated space and select “Create Partition”.

Create Partition

2. In the pop-up window, you can set the partition size, drive letter and file system for the new partition. To adjust the partition size, you may drag the right or left edge of the partition as shown below. For more settings like partition label and partition type (primary or logical), you may click “Advanced<<” button.

New Partition Size

3. Click “Apply” to view pending operations and then “Proceed” to commit the operations.


✔Recover partitions

1. Click on “Partition Recovery Wizard” on the left-hand pane. Choose the USB disk from which you want to recover the accidentally deleted or lost partitions. Click “Next” to continue.

Partition Recovery Wizard

Select Disk

2. Select a search mode in the pop-up window. “Fast search” is recommended for saving time.

Two Methods

Tip: If you can’t find those deleted or lost partitions by “Fast Search”, try another way: Full Search.

3. Tick the partition which you want to recover and click “Proceed” to execute the operation.


Situation 2. USB pen drive in RAW

This error can be fixed by reformatting the USB flash drive. Keep in mind that format will destroy all the data stored on the USB drive, so it’s essential to back up all the important files and data before you do. The free backup software—AOMEI Backupper Standard could help you create a backup for those data. Now follow the guidance below:

1. Right click the USB pen drive that you need to format and hit “Format Partition”.

Format Partition 64gb

2. In the pop-up window, you can name the USB drive by editing “Partition Label” and change file system based on your needs. Click “OK” to continue.

Select File System 64gb

Tip: FAT32 ensures cross-platform compatibility while NTFS supports a single file size over 4GB.

3. Click “Apply” to view pending operations and then “Proceed” to commit the operations.

Apply Proceed 64gb

Note: You can also fix “unable to format external hard drive RAW” via AOMEI Partition Assistant command lines.

Situation 3. USB pen drive is assigned a used drive letter

This issue can be resolved by changing the drive letter:

1. Right click the USB pen drive which you want to give a new drive letter to, select “Advanced” and then “Change Drive Letter”.

Change Drive Letter

2. Select a new drive letter in the pop-up window. You can choose whichever drive letter you like except the ones that are occupied by other drives.

Select New Drive Letter

3. Click “Apply” to view pending operations and then “Proceed” to commit the operations.



Now you know how to repair pen drive not detected. You can find the corresponding solution according to the exact cause from this page. With AOMEI Partition Assistant, you are able to convert primary partition to logical in Windows 7, fix Windows 7 blue screen after SSD install and so on. Go for this tool and you won’t regret!